As a personal trainer my clients ask me about similar products to this one. I think that rather than telling them what I have read and claims about the product it is more fair to try it myself.
I think the belt is very good as it offers great lower back support (although not its main intention) makes you loose ALLOT of excess water around your waist and improves posture slightly during workouts by making you more aware of your core.
I mix my workouts up beween mountain running and weight training and this product is the only thing that stays the same. Been using for a month now - not massive results but give it a go as I think it definately helps (along with a good diet and excercise program) I think people expect miracles with similar products but there is no substitute for hard work.
This means that it wont work if you eat a takeaway, wear it to walk the dog and expect a six pack.
For the price I would recommened it to anyone.